1. Field of the Invention
The present invention relates generally to fiber-optic inertial sensors such as linear and angular accelerometers, and particularly Sagnac ring interferometers and closed-loop angular motion sensors utilizing such interferometers.
2. Description Of Related Art
A traditional Sagnac ring interferometer is a single-fiber interferometric sensor which divides a light beam and propagates it in opposite directions around a multi-turn coil of single-mode optical fiber. Then when the coil is rotated, the two counter-propagating beams undergo equal and opposite phase shifts. The two-phase shifted beams are then re-combined to convert the phase differences to an intensity-modulated light signal whose intensity is proportional to the rate of rotation, i.e., the angular velocity, of the coil.